import { nextTick, ref } from 'vue'

export function useScroll() {
  const scrollRef = ref(null)

  const scrollToBottom = async () => {
    await nextTick()
    if (scrollRef.value) {
      scrollRef.value.scrollTop = scrollRef.value.scrollHeight; 
    }
  }

  const scrollToTop = async () => {
    await nextTick()
    if (scrollRef.value)
      scrollRef.value.scrollTop = 0
  }

  const scrollToBottomIfAtBottom = async () => {
    await nextTick()
    if (scrollRef.value) {
      const threshold = 1000 // 阈值，表示滚动条到底部的距离阈值
      const distanceToBottom = scrollRef.value.scrollHeight - scrollRef.value.scrollTop - scrollRef.value.clientHeight
      if (distanceToBottom <= threshold) {
        scrollRef.value.scrollTop = scrollRef.value.scrollHeight
      } 
    }
  }

  return {
    scrollRef,
    scrollToBottom,
    scrollToTop,
    scrollToBottomIfAtBottom,
  }
}
